Atomistic and Microstructural Computational Fatigue Design and Integrated Creep-Fatigue Theory for High-Temperature Alloys

高温合金的原子和微观结构计算疲劳设计和集成蠕变疲劳理论

• 批准号: RGPIN-2019-06264
• 负责人: Liu, Rong
• 金额: $ 2.33万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=715797
• 关键词: Atomistic; Microstructural; Computational; Fatigue; Design

Fatigue accounts for at least 90 percent of all service failures of components subjected to cyclic loading, as experienced by automobiles, aircraft, compressors, pumps, turbines, etc. Traditionally, engineers and researchers have to perform testing to determine a material's fatigue property, which results in high costs in time and money, thus prolonging the development cycle in material and component design for mechanical/structural systems. Recent research has reported that the low cycle fatigue (LCF) life of a material can be formulated in terms of material's physical properties including Burgers vector, shear modulus and surface energy. High cycle fatigue (HCF) is, in essence, a process of microstructural LCF crack nucleation plus crack propagation. Enlightened by these understandings, a computational fatigue design approach is proposed in the present research, aiming to search for new high-temperature alloys with superior fatigue resistance. A microstructure-based numerical model combined with first-principles density functional theory (DFT) will be developed and then used to predict the crack nucleation life of polycrystalline metals for a wide spectrum of loading from LCF to HCF. Furthermore, utilizing the deformation mechanisms involving glide and climb of dislocations within grain interior and along grain boundaries, a holistic theoretical framework the integrated creep-fatigue theory (ICFT) for high-temperature alloys will also be proposed in the present research. The theoretical model established based on the first cornerstone leads to constitutive laws encompassing all possible deformation mechanisms and that based on the second cornerstone describes the damage accumulation process leading to fracture, and thus defines the life under general loading conditions that involve a combination of fatigue, creep and thermomechanical fatigue. Using this theory, only limited laboratory-testing will be required for a new material development such that material behavior under complicated loading conditions can be linked to the fundamental deformation mechanisms. Once established, the proposed theory and model will speed up material development and application to meet the fast-growing technological demands and stringent environmental requirements in the 21st century and future. They also have a great implication in prognosis and health management of existing or newly designed mechanical systems, with accurate life prediction, offering tremendous savings in life cycle management. In addition to the benefits for the research field, the proposed research has also planned the training of Highly Qualified Personnel (HQP) with serious consideration of Equity, Diversity and Inclusion (EDI). The time and cost saving using this research outcomes to design new materials and maintain mechanical systems to meet continuously increasing requirements for the gas turbine industry will certainly benefit and contribute to the economy and society of Canada.

疲劳至少占所有服务失败的90％的组件，构成了经过循环负荷的所有服务失败，这是由汽车，飞机，压缩机，泵，涡轮机等所经历的。传统上，工程师和研究人员必须执行测试以确定材料的疲劳特性，从而导致时间和金钱的高成本，从而在材料和组件中促进材料和组件设计的高成本。最近的研究报告说，材料的低周期疲劳（LCF）寿命可以根据材料的物理特性（包括汉堡矢量，剪切模量和表面能量）来制定。高循环疲劳（HCF）本质上是微结构LCF裂纹成核和裂纹传播的过程。通过这些理解的启发，本研究提出了一种计算疲劳设计方法，旨在寻找具有出色疲劳性抗性的新高温合金。将开发基于微观结构的数值模型与第一原理密度功能理论（DFT），然后用于预测从LCF到HCF的各种载荷的多晶金属的裂纹成核寿命。此外，利用涉及滑行和沿晶界内的脱位的变形机制，在本研究中也将提出整体理论框架的整体理论框架。基于第一个基石建立的理论模型会导致构成所有可能的变形机制的本构定律，并且基于第二个基石，描述了导致断裂的损伤积累过程，因此在一般加载条件下定义了寿命，涉及疲劳，蠕变，蠕变和热力学疲劳的组合。使用该理论，新的材料开发只需要有限的实验室测试，以便在复杂的负载条件下的材料行为可以与基本变形机制有关。建立后，提出的理论和模型将加快材料开发和应用，以满足21世纪和未来的快速发展的技术需求和严格的环境要求。它们还对现有或新设计的机械系统的预后和健康管理具有很大的影响，并具有准确的生活预测，从而为生命周期管理提供了巨大的节省。除了对研究领域的好处外，拟议的研究还计划对高素质人员（HQP）进行认真考虑，多样性和包容性（EDI）的培训。使用这项研究成果节省时间和成本，以设计新材料并维护机械系统，以不断地满足燃气轮机行业的需求，这无疑会受益并为加拿大的经济和社会做出贡献。